Disposable absorbent articles such as diapers, incontinence articles, catamenial devices, training pants and the like are well known in the art. Typically, disposable absorbent articles comprise a liquid pervious topsheet that faces the wearer's body, a liquid impervious backsheet that faces the wearers clothing, an absorbent core disposed between the liquid previous topsheet and the backsheet, and means to keep the core in fixed relation to the wearer's body.
In order to absorb and contain bodily exudates such as urine, feces or menstrual fluids, an absorbent article must cover (i.e. occlude) certain parts of a wearer's body. Generally, current absorbent articles cover even larger parts of the wearer's body than may be necessary for absorption alone to allow for adequate storage of the exudates and to maintain the absorbent article in a proper position relative to the wearers body for such absorption.
While this coverage is an essential element of the functionality of the article, skin occlusion due to wearing the article also can, in addition to negatively impacting wearer comfort, cause negative changes to wearer skin structure. For example the pressure exerted by elastic elements in absorbent articles of the current art can cause red marking. Also, occlusion of the skin by the absorbent article can, potentially, lead to skin overhydration with resulting increased risk of skin irritation. Further, as skin becomes overhydrated, it becomes macerated. As a result, overhydrated skin is more susceptible to damage from abrasion due to rubbing caused by normal wearer movements (i.e. chafing). Such susceptibility to skin disorders, including diaper rash, erythema (i.e. redness), heat rash, abrasion, pressure marks and skin barrier loss is well known. For example, 21 C.F.R. 333.503 defines diaper rash "[a]n inflammatory skin condition in the diaper area (perineum buttocks, lower abdomen, and inner thighs) caused by one or more of the following factors: moisture, occlusion, chafing, continued contact with urine or feces or both, or mechanical or chemical irritation."
Said another way, the stratum corneum is the skin layer that, almost exclusively, provides the water barrier properties to the skin. Thus, any environmental condition that can increase the hydration state of the stratum corneum will, in all likelihood, lead to overhydration. As noted above, occlusion by an absorbent article is a prime example of an environmental condition that can lead to overhydration. In particular, skin occluded by an absorbent article sees at least the following differences in its environment when compared to unoccluded skin:
Available water from bodily fluids, such as urine, increases the driving force across the extra cellular lipid component of the stratum corneum (the hydrophobic component which provides the main water barrier properties to the stratum corneum) allowing the keratin enriched corneocyte component of the stratum corneum (the hydrophilic component which provides mechanical strength to the stratum corneum) to become overhydrated. Such available water can come from inadequate acquisition by the absorbent article, from rewet because the absorbent article falls to have adequate liquid retention capability or from sweat due to the occlusive nature of the absorbent article. PA1 Increased relative humidity in the void volume between the absorbent article and the skin can interfere with the natural transport of water vapor into and out of the skin. As is well known, mass transport depends on a concentration differential across a barrier. If the relative humidity on the outside of the stratum corneum becomes too high and additional water is delivered to the body side of the stratum corneum (e.g. due to an increase in ambient temperature) the water will remain in/on the skin a longer period of time. PA1 Once the skin begins to become overhydrated, the barrier properties of the extra cellular lipid component of the stratum corneum begin to degenerate. PA1 More or less breathable devices or materials are described in U.S. Pat. Nos. 4,627,847, 4,648,876, 4,578,069, 4,713,068, 4,758,339, 4,833,172, 4,923,650, 5,254,111, 5,492,751, 5,599,420 and 5,628,737, in published European Patent applications EP 315,013 and EP 710,471, and in published PCT applications WO 95/16,562 and WO 95/16,746. Generally, all such devices or materials balance gas permeability and liquid impermeability. This becomes particularly apparent when considering materials having apertures or pores, whereby an increase in pore size will allow easier gas permeation, but also easier liquid permeation. The latter may be undesirable, in particular, when such materials are used as backsheet materials to cover liquid retaining regions of an absorbent article, such as the core region thereof In particular, for articles designed to absorb larger quantities of liquids, such as baby or adult incontinence devices, approaches aimed at keeping only part of the article breathable, such as by covering the liquid absorbing parts (often referred to as absorbent core) by a non-breathable material, but having other parts of the article made of breathable materials have been used. PA1 The art has also used "lotions" in combination with absorbent articles. Examples include: U.S. Pat. No. 3,585,998 to Hayford et al.; U.S. Pat. No. 3,464,413 to Goldfarb et al.; U.S. Pat. No. 3,896,807 to Buchalter; U.S. Pat. No. 3,489,148 to Duncan et al.; and U.S. Pat. No. 5,643,588 to Roe et al. While such attempts may provide a "lotion", devices of the current art have either failed to transfer an amount of lotion that is effective against overhydration or to even recognize that lotion applied to an absorbent article may be effective against overhydration. PA1 The art has also focused on providing absorbent cores that are effective in acquiring, distributing, and storing discharges of bodily fluids. Such devices are described in, for example: U.S. Pat. Nos. 4,898,642 and 4,798,603; Published European Patent applications EP 640,330 and EP 397,110; and in many other patents and published applications. In previous attempts aimed at improving the interaction between absorbent articles and the skin of the wearer, the art has not sufficiently recognized that there can be cooperation between good rewet performance of the absorbent article and material transport through backsheet materials which can result in improved skin condition.
Such degeneration results in increased overhydration, leading to compromised skin and, even, diaper rash (diaper dermatitis).
While the art has approached this problem in various ways (see below), it has failed to recognize that improving protection against skin overhydration due to wearing an absorbent article (i.e. maintaining the skin occluded by an absorbent article in a state more like the state of unoccluded skin) is multifunctional in nature. As is discussed in the various objects for the present invention, skin can best be protected against overhydration by addressing all (or as many as possible) of the sources of overhydration at one time.
Numerous attempts have been disclosed that are directed to improving wearer skin condition by reducing the risk of creating overhydrated skin or by allowing already overhydrated skin to dehydrate to a level closer to unoccluded skin. For example:
While, as is clear from the above, the art has continually attempted to improve various individual aspects of absorbent articles, as such aspects may relate to maintaining a wearer's skin in a condition more like that of unoccluded skin, the art has failed to recognize that such aspects may cooperate to provide even further improvement in wearer skin condition.
Thus, it is an object of the present invention to provide disposable absorbent articles that provide a skin condition benefit to a wearer's skin. In particular, it is an object of the present invention to provide absorbent articles that help maintain a wearer's skin at a hydration level that is more like the hydration level of unoccluded skin than absorbent articles of the current art. It is a further object of the present invention to provide such hydration level maintenance by providing absorbent articles having cores with particularly good fluid handling performance (in particular the rewet characteristics of such cores). It is still a further object of the present invention to provide such absorbent articles with vapor permeable backsheet materials so as to reduce the relative humidity in the void volume between the absorbent article and a wearer's skin. It is yet a further object of the present invention to provide such absorbent articles with a body contacting surface (e.g. a topsheet, a cuff, or the like) comprising a skin care composition at least a portion of which can transfer from the body contacting surface to a wearer's body to provide a skin condition benefit (e.g., providing a barrier to any residual moisture remaining on the wearer's skin so such residual moisture is less deleterious to the wearer's skin condition). It is still a further object of the present invention to provide a single absorbent article comprising such improved absorbent cores, such permeable backsheets, and such topsheets. These and other objects may be obtained by using the present invention as will be taught in the following disclosure.